May 10th, 2013 11:57 AM

Miami Heat’s Dwyane Wade and LeBron James warm up before facing the Chicago Bulls in Game 2 of their NBA basketball playoff series in the Eastern Conference semifinals on Wednesday, May 8, 2013, in Miami. (AP Photo/The Miami Herald, Charles Trainor Jr)

Parity has struck the NBA playoffs, where the conference semifinals are all fit to be tied.

The four current series are all knotted at one game apiece – the first time that’s happened in the second round of the NBA playoffs since the league went to its current format more than a quarter-century ago. For favorites like Miami, New York, San Antonio and Oklahoma City, home-court advantage has disappeared, and now it’s the underdogs who can control their own fates simply by taking care of business on their home floors.

A wild weekend is ahead, without question.

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The Heat, Knicks, Spurs and Thunder are four of the league’s top five winningest road teams this season. That probably isn’t being received as great news for Chicago, Indiana, Golden State and Memphis, the lower-seeded clubs who will be hosting pivotal Game 3’s when NBA playoff action resumes on Friday and Saturday.

“Pretty cool. The NBA’s loving it,” Heat forward LeBron James said. “When it comes to the playoffs, I always continue to say no matter how many games you win or lose in the regular season, once you get to the playoffs everybody’s record is 0-0. So I think it’s great. I think it’s great for our fans, I think it’s great for the competition that every series is tied 1-1.”

After a first round with only two sweeps – by Miami and San Antonio, probably the favorites in the Eastern and Western Conferences, especially after Oklahoma City lost Russell Westbrook to a knee injury – the tone for the second round was set pretty quickly around the league. Miami lost Game 1 at home to a wounded and weary team from Chicago. San Antonio needed a huge comeback to beat Golden State in Game 1 of their series, then saw the Warriors simply come back and take Game 2.

The Knicks lost Game 1 to Indiana before evening up their matchup, and the Thunder are likely feeling lucky that they’re not in an 0-2 hole after Memphis had plenty of chances to take the opening game of their series.

“When you get this deep into the playoffs, they’re all good teams, they’re all very good teams more than capable of winning at home or on the road,” Golden State coach Mark Jackson said. “So I’m not surprised at all. Good coaching, good playing, you make adjustments and win games. They’ve all been great games.”

Big fourth-quarter comebacks, first by Oklahoma City and then by Memphis, decided the outcomes of the first two games of that series, where the cumulative score right now is Grizzlies 190, Thunder 186. The first two Spurs-Warriors games were pure theater, with San Antonio winning a double-overtime thriller in Game 1 after rallying from 16 points down late in regulation.

Road teams took Game 1’s in the East semifinals, with Indiana and Chicago both winning by seven. And the home teams imposed their wills in Game 2 of both matchups, New York using a huge late run to beat the Pacers by 26, and the Heat outscoring the Bulls by an unbelievable 62-20 margin over a 19-minute stretch on the way to evening that matchup with a 115-78 romp.

“Anybody can beat you on a given night and playoff basketball is no different,” Knicks coach Mike Woodson said. “I mean, everybody at this particular time is hungry even more. Nobody wants to go home so it becomes crazy basketball. Everybody is pumped up and ready to play.”

Then again, if you checked out how these teams fared against each other in the regular season, maybe you could have seen something as uncanny as this coming.

There wasn’t any real separation between the clubs then, either.

The Bulls and Heat split four games against one another, as did the Knicks and Pacers, and Spurs and Warriors. The only exception was Memphis beating Oklahoma City in two of the three games they played this year – and if they met four times, there would figure to be a chance that it could have been a 2-2 split as well.

“Each team is working hard, trying to get wins,” said Memphis guard Tony Allen, who was part of Boston’s title-winning team in 2008. “They got the trophy on their mind so I believe that each series is probably going to go all the way to the end. You look at the eight teams that are left, all the teams have a shot.”

The Heat entered the playoffs as the overwhelming favorites to win their second straight title, and they remain that way in the eyes of oddsmakers even though they’ll need to win one game in Chicago to reclaim the home-court advantage.

Heat coach Erik Spoelstra’s eyes widened a bit Thursday when told that no second round in the NBA playoffs had ever opened quite this way.

“Is that right? First time ever? Really? Wow,” Spoelstra said. “Makes for great theater. I know I’m enjoying the other games, probably like other fans are enjoying ours. It shows how much parity there is and how little margin for error with the teams that are left. … We had always felt there was up to six or seven legitimate, title-contending teams.”

The way things look, maybe there’s eight now.

“It looks like it’s the best eight teams in the NBA right now,” James said. “So we’ll see what happens.”